Embodiments of the present invention relate generally to a turbo-machine and more particularly relates to an aspirating face seal used in the turbo-machine.
Typically, face seals are used to minimize leakage of a pressurized fluid through a gap between two components from a region of higher pressure to a region of lower pressure in a turbo-machine. Such seals have been used in rotating machines, for example, a steam turbine, a gas turbine, or the like. In applications such as gas turbine engines, aspirating face seals are used to minimize leakage of a fluid such as compressed air or combustion gases between a rotor and a stator. The face seals disposed in the gaps or leakage paths between the stator and the rotor are configured to compensate for variations in the gaps due to differential thermal and mechanical component expansions during the machine operating cycle.
Conventional aspirating face seals typically have mutually facing rotatable and non-rotatable seal elements. The rotatable seal elements are coupled to or form a monolithic portion of the rotor. The non-rotatable seal elements are coupled to a portion of the stator and movable axially. The rotatable and non-rotatable seal elements are generally annular, and perpendicular to a longitudinal axis of the rotor.
During operation, the aspirating face seals typically operate with a tight clearance between the non-rotating seal elements and rotating seal elements. Under normal operating conditions, no contact is expected to occur between the non-rotating seal elements and rotating seal elements. However, under extreme circumstances, contact between the non-rotating seal elements and rotating seal elements may occur.
Therefore, it is desirable to have an aspirating face seal assembly that retracts a seal in the event of such a rub between non-rotating seal elements and rotating seal elements.